The present invention relates to an improved construction of filtration media of a wedge filter providing a performance on both surface and inner filtration mechanisms with offering many times recycled use by washable functions. Particularly a wedge filter plate is used to construct a hollow cylindrical type media of wedge filter. The whole construction of a wedge filter plate of the present invention is a flat plate with a web pattern manufactured by several different radius wedge-shaped strings of concentrically circular arc and several radial struts. The radial sedimentation chambers are established between each adjacent different radius wedge-shaped string. The sectional view of a wedge-shaped string is wedge or triangle. The thickness of a wedge-shaped string is less than a radial strut of the wedge filter plate. When wedge filter plates are laminated so as to construct a hollow cylinder, the differences of thickness become wedge-shaped apertures between each adjacent plate, and these filtering apertures of circular arc constitute a plurality of concentrically cylindrical filter screens with different radius. The sedimentation chambers are between each adjacent filter screen whereby to separate each filter screen. The mesh size of filter screen can increase progressively either from inner filter screen to outer filter screen or from outer filter screen to inner filer screen. The particles of different size are classified according to filter screens of different mesh size and left in the sedimentation chambers to accumulate filter cakes, which approaches the performance of applying a series of filter screen with different mesh size. When filter cakes accumulate excessively, it only needs to take the filtration media out, loosen the nuts at the ends of rod, and wash each individual filter plate completely. When all done, reassemble and tighten all elements up, then the filtration media can be reused.
1. Technical Field of the Invention
The present invention focus its efforts on developing an improved construction of filtration medium of a wedge filter, which particularly focus on a wedge filter plate which is used to construct a hollowly cylindrical filtration medium. The construction of the wedge filter plate is manufactured by several concentrically wedge-shaped strings of different radius that constitute concentrically multi-layered filter screens to classify the particles of different size, then deposit them in sedimentation chambers established between each adjacent filter screen and form filter cakes in order to promote the efficiency of water treatment greatly.
2. Prior Art Technique
Currently, the wedge filter is popular used in industrial fluid filter system and residential drinking waster filter system, especially a use of a device for pre-filtration to remove large particles, and the wedge filter is used widely in a need for only removing particles that are above 10s μm. The reason of the wedge filter is used widely substantially in many field is its virtues of the filter surface of easy wash, large volumes of outflow, and low filtration pressure.
FIG. 1 shown a wedge filtration media (01) of a filter is manufactured by winding a stainless steel wedge wire (02) in an equal interval pitch into a spiral cylinder of same radius, and there are several axial stainless steel struts (03) inside the cylinder to fix the stainless wire (02) by welding to enhance the wedge filtration media (01) strength to withstand high operation pressure during the filtration process. The mesh size of a wedge filtration media (01) is determined in course of production and based on the axial pitch between each adjacent wire, in other word, the aperture between each adjacent wire is the size of the mesh, and the minimum size is 0.025 mm. It costs expensive to make a wedge filtration media (01) because the production process is very precise. The wedge filtration media (01) adopts surface filter system that causes filter cakes to easily accumulate on the filter surfaces, which increases the filtration pressure and decreases the filtered outflow volume. Therefore, a periodical removal of filter cakes becomes an important job for the wedge filtration media (01), for this reason, the inventions of a wedge filtration media always focus on how to reduce the growth of filter cakes in order to lengthen the periodicity of re-washing. Two of most popular methods for washing the wedge filtration media (01) are hand washing and mechanical cleaning. The wedge filtration media (01) with small mesh needs a high pressure water flow or high pressure air to spray washing on reverse side by hand, but for industrial purpose of large volume of flow and continuous filtration usually employ the cleaning mechanism, such as:                1. A use of parallel filtration mechanism to reduce filter cakes growth, U.S. Pat. No. 4,311,591.        2. A use of a self-cleaning brush mechanism to remove filter cakes, U.S. Pat. No. 6,861,004 B2.        3. A use of rotational bar to shake the filtration media continuously to reduce filter cakes growth, JP9024216.        4. A device of synchronous reverse washing for the filtration media cylindrical surface.        
Since the mesh size of the wedge filtration media (01) is uniform, thus the tempo and the thickness of filter cakes accumulation become important factors in affecting the filtration efficiency. The cleaning methods described above are rarely employed for residential purpose or other medium and small size filter system because of the facilities cost and the filtered flow volume.
Besides the methods described above, increasing the filtering surface is also a popular method, such as:                1. A use of a series of wedge filters with different mesh size to lengthen the periodicity of washing and promote the efficiency of filter system.        2. A use of concentric C-shaped wedge filtration media, US2006/0201873 A1.        
From prior art technique described above, there are some solutions were addressed successively for the wedge filter, but for residential purpose of medium and small size still has some issues needed improvement as the following:                1. A wedge filtration media is manufactured by winding a stainless steel wedge wire and formed by welding, the process of production is high precise and costs expensive.        2. The surface filter system of uniform mesh size causes filter cakes easily formed and increasing filtration pressure needed. Therefore, applying a series of wedge filters of different mesh size becomes a necessary method for lengthening the periodicity of washing.        3. A wedge filtration media of small mesh has a need of applying reverse high pressure water flow or high pressure air to spray washing on reverse side or use a small brush to clean.        
The reason of a conventional wedge filter till popular now is its virtues of strength, large volume of flow, and reusability. The present invention not only retains these previous advantages, but also has developed several innovative virtues, such as easy production, low cost, series filtration mechanism to reduce filter cakes growth and easy to wash, so that the wedge filter of the present invention will be helpful for end user and more widely application.